The film Cold Souls takes the unusual position that souls are an impediment to joyful humanity, rather than the seat of it. If we could just shake loose of our souls for a time, we might become who we really are. It’s a premise worthy of Charlie Kaufmann, but first-time writer/director Sophie Barthes has simpler aims in mind. Sure, her protagonist is the actor Paul Giamatti playing himself (Sideways, American Splendor) as he struggles with the title role in Chekov’s Uncle Vanya, but Barthes favors the coolly emotional over the densely referential. Frustrated with his career, Paul turns to soul removal, a new procedure he hears about from his agent. After a consult with Dr. Flintstein (David Strathairn), Paul orders up a “plain extraction,” during which he is inserted into what looks, fittingly enough, like a giant tooth-shaped MRI machine. The removal leaves behind just enough soul residue “to keep him animated,” says the good doctor, the implication being that soul extraction resembles taking an anti-depressant.

I don’t know if anyone does brooding self-hatred better than Paul Giamatti. Following the procedure, he’s clearly different somehow, even if those differences are hard to isolate. What is clear is that he can no longer act. He says he feels lonely and hollow; his wife Claire (Emily Watson) says he smells funny. Complicating matters is that Paul doesn’t reveal his soul extraction to Claire right away. Meanwhile, a group of Russian soul mules — temporary carriers — are running a fledgling business trafficking souls into America. When Paul can no longer stand his emptiness, does he restore his own soul? Not at all. He “rents” an anonymous soul of Russian origin from a Soul Catalogue, at which point Cold Souls starts to get under your skin. Barthes and director of photography Andrij Parekh (Half-Nelson) keep things off-kilter without losing their balance. Paul, who can’t contain the misery of his new soul, requests his original soul back. The problem is that the Russians have it, only they think it belongs to Al Pacino.

While owing a great debt to Being John Malkovich, Barthes has created a philosophical comedy much lighter than the films that inspired her. Cold Souls is bright and intelligent; its primary weakness is that the Russian subplot, which begins with a flourish, soon feels like an afterthought. (So do the actresses Watson and Lauren Ambrose, both used for dressing here.) Giamatti, meanwhile, eases into his role in a number of surprising ways. Instead of weighing down the story with his misery, he lightens the production by playing for farce. The conversation in which he divulges his procedure to Claire is delightful. So is his reaction when he realizes his soul has been stolen; his may be the funniest face of the year. A film about confronting fear and distress, about the perils of tinkering with ourselves and ultimately about the beauty of accepting who we are, Cold Souls is a modest invention, but all the more enjoyable for that.